Given the sheer size and weight of commercial driven machines such as industrial, mining, earth-moving and construction machines, the steering of these machines is generally executed hydraulically. In other words, steering commands from the operator are translated into a degree of movement or an absolute steering angle, and the requisite movement is accomplished via hydraulic power with little or no force assistance from the operator. Such hydraulic steering systems certainly ease operator strain and fatigue, and in many cases are necessary for the operator to be able to steer the machine at all.
However, there are certain failure scenarios that can disable a hydraulic steering system. For example, such systems rely on the presence of high pressure hydraulic fluid, which is generally supplied by a steering pump. The steering pump is in turn driven by the engine or other primary power source for the machine. If the engine stops or is lugged down below a certain rpm level, the steering pump may not operate, or may run too slowly to operate the steering system.
With this in mind, some hydraulic steering systems employ a secondary steering pump to back up the primary steering pump. The secondary pump may be electrically driven, since the most common failure mode for the primary pump would be loss of engine power. However, such secondary pumps incur an additional expense, and as such are typically not capable of repeated or frequent use. In addition, in some cases, secondary steering pumps are output driven, but this may cause undesirable additional losses in the overall system.
The present disclosure is directed to a system and method to improve hydraulic steering operations in order to address one or more of the problems or shortcomings set forth above. However, it should be appreciated that the solution of any particular problem is not a limitation on the scope of this disclosure or of the attached claims except to the extent expressly noted. Additionally, this background section discusses problems and solutions noted by the inventors; the inclusion of any problem or solution in this section is not an indication that the problem or solution represents known prior art except as otherwise expressly noted.